The original feldspar 1886 formula Bon Ami can leave micro scratches in glass as well, if used regularly.
I suppose anything can scratch glass if you are not gentle. I do it once a month or so, wet the windshield first, sprinkle a small amount and wipe it gently with a microfiber sponge not scrub it like I am trying to remove a layer of paint.
No visible micro scratches at nigh .
Ace hardware usually doesn't have it in stock but they do carry it and will order it for you to pick up in store with no shipping charges, they also have Sno Seal cheap if you order it.